Method and apparatus for spinning organic high polymers



Sept. 9, 1969 H. SCHIPPERS ET 3,466,357

METHOD AND APPARATUS FOR SPINNING ORGANIC HIGH POLYMERS Filed Dec. 7, 1966 x 5 Sheets-Sheet 1 FIG. I

I1 W1." LS. HEINZ SCHiPPERS KARL OSTERTAG ATT'YS Sept. 9, 1969 H.SCH|PPERS ETAL 3,466,357

METHOD AND APPARATUS FOR SPINNING ORGANIC HIGH POLYMERS Filed Dec. 7, 1966 3 Sheets-Sheet. 2

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HEINZ SCHIPPERS- KARL OSTERTAG ATT'YS.

Sept. 9, 1969 H. SCHIPPERS ET AL METHOD AND APPARATUS FOR SPINNING ORGANIC HIGH POLYMERS 5 Sheets-Sheet Filed Dec. 7, 1966 FIG.

N mi i x x .i i w 4 \M H u v n {I n Ad R A/ HEINZ SCHIPPERS KARL OS ER AG ag (f/A ffis United States Patent 3,466,357 METHOD AND APPARATUS FOR SPINNING ORGANIC HIGH POLYMERS Heinz Schippers, Remscheid, and Karl Ostertag, Wuppertal-Barmen, Germany, assignors to Glanzstofi AG,

Wuppertal, Germany Filed Dec. 7, 1966, Ser. No. 599,782 Claims priority, applica tigg Gezrmany, Dec. 18, 1965,

Int. Cl. B29f 3/ 08; D01d 5/10 U.S. Cl.v 264-176 7 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to a process for spinning organic polymers, in particular quickly decomposing or strongly afterpolymerizing polymers, by means of fusion spinning installations heated with a liquid or gaseous medium.

As is well known, spinning interruptions and differences between the individual capillary tubes as well as differences in the thread qualities are often caused by the shortcomings of the employed melt spinning installations. Of particular importance is the temperature distribution within the nozzle unit where, for example, because of the relatively good heat transfer between the nozzle plate and the thin melt filaments emerging through the bores, the temperature distribution in the nozzle Plate itself has proved to be of great importance.

Difficulties of a special kind result where certain high viscosity polymers are spun, for example, polyesters with high solution viscosity. If they are heated only enough that during the period of dwell in the spinning head the degradation of the chains stays Within tolerable limits, spinning difiiculties and unsatisfactory thread qualities are the result. If the heating takes place to the point where good spinning is possible, however, degradation within the spinning apparatus becomes very substantial and the quality of the filaments is generally considerably below the quality obtainable from the original material.

The above problems have not been overcome through the use of known devices. For this reason the employed methods characteristically represent a compromise between the necessity of having to heat the melt up to a good spinnability point and to as low a temperature as possible for maintaining the favorable ualities of the initial product.

An essential reason for the shortcomings of the known methods and installations for the spinning of organic high polymers lies in the fact that the heating of a portion of the melt spinning installation, in particular the heating up of the nozzle unit, had to take place principally through the melt itself. Because of this, the installation was not only strongly dependent on the spun titer, i.e., on the specific throughput quantity, but other disadvantages also became evident. For example, a melt spinning head became known in which the nozzle unit was set into a recess in the heating box enclosing the I of only 3 mm. which 3,466,357 Patented Sept. 9, 1969 pump block from below and tightly pressed against the pump block. A heat-conducting connection between the nozzle block and pump block existed only at the relatively small sealing surface since air gaps existed between the heating box walls and the nozzle package. Consequently, except via the small connection at the sealing spot, at the entire circumference heat could only arrive in the nozzle package through radiation while the reflection in particular of the nozzle plate towards the bottom was considerable. Consequently, this installation was practically not suitable for the spinning of quickly decomposing, highly viscous polymers such as, for example, polyesters with high dissolving viscosity, or of such high polymers which are prone to strong subsequent condensation or subsequent polymerization since in order to guarantee good spinnability the temperature at the entry into the nozzle package still had to lie above the optimum spinning temperature.

In the case of another melt spinning installation which has become known, the unit consisting of filter, bracket plate and nozzle was placed in the heating box from above. The delivery of the melt took place from the side. Opposite to the inlet, a pressure mechanism was set up which pressed a sealing surface existing at the so-called packet against the melt line. Therefore, a ring slot around the nozzle unit could not be avoided so that the heating of the latter took place through radiation. Metallic contact existed only in the small sealing surface and possibly still at the place of contact with the pressure spindle. Normally, the air gap had a width of approximately 1 mm. which resulted in temperature differences between heating medium and nozzle plate edge of approximately 7 C. (depending upon the spinning temperature). But this also led to the result that, since the melt inlet was partially heated in a stronger manner than the nozzle unit, the temperature of the melt was actually above the proper spinning temperature during a portion of its travel because of the higher temperature of the heat medium required to obtain a sufficiently high nozzle temperature. A further, especially serious disadvantage was added to this. Through the deformation of the sealing during the holding down of the nozzle unit it cannot be avoided that this unit sat eccentn'cally in the heating box bore in a manner which could not be predetermined. This had to lead to temperature differences in the nozzle plate influencing the spinning process noticeably and disadvantageously. For example, in the case of an eccentricity was, as known from experience, very often exceeded, a temperature difference of approximately 2 C. between the nozzle plate edges opposite to the spot of the most narrow and to the spot of the widest slip could be detected.

It is an object of the present invention to eliminate the disadvantages set forth above, in particular by a method and apparatus in which direct heating of the nozzle unit from the side of a nozzle plate of known construction is accomplished as well as uniform heating of the nozzle plate. The heating box temperature to be selected is substantially independent of the throughput rate. In addition, the faultless spinning of polymers which either decompose quickly or after polymerize in undesired manner at high temperatures is made possible without damage to or undesired change in their structure.

According to the invention, the desired results are obtained by a method utilizing melt spinning installations heated with a liquid or gaseous medium wherein the heating of the conveying means and of the spinning unit is undertaken separately by conduction and through heat radiation below the thread outlet and parallel, or approximately parallel, to the emerging threads, heat which works against the radiation of the nozzle surface is supplied over the emitting surfaces. In a development of the invention, in particular where polymers are spun which are subject to rapid degradation or strong afterpolyrnerization or subsequent condensing at spinning temperatures, the polymers are fed to the spinning installation with a melt temperature which is below the spinning temperature and are heated to the spinning temperature immediately before the thread formation.

Such a procedure has proved to have advantages. On the one hand the degradation of polymers with high molecular weight and high viscosity, for instance of polyesters with high solution viscosity, and/ or the afterpolymerization are substantially slowed, while on the other hand it becomes possible to spin fibers having improved and more uniform properties. The procedure according to the invention is applicable to all organic polymers which can be spun. It has become evident, however, that heating according to the invention is separated cycles is especially valuable when the danger of degradation or afterpolymerization is great. In each case heating the nozzle unit with good contact over a large area causes the heating of the nozzle unit to become practically independent of the heat which is transferred by the melt and causes the temperature to be uniformly divided over the surface of the nozzle. Additionally, the temperature difference between the heating medium and nozzle is very small.

The following examples illustrate the advantages of the invention. In addition to the spinning installation according to the invention, a known spinning installation up to now used on a large scale, with a nozzle unit which can be inserted from the bottom and feeding of the melt from the top was employed. In all cases nylon 6 was spun.

Example 1 Measurements for comparison with the known equipment for melt spinning should make clear the importance of the metallic contact, that is, the contact which transfers the heat very well at the sealing area of the nozzle unit and the melt conduit. Between the nozzle unit and the melt conduit in one case aluminum rings were used while in the other case rings made of material which does not readily conduct heat were used.

From this table it can be seen that the heat transfer even over the small contact area of the sealing has an important influence on the temperature of the nozzle plate and melt.

Example 2 In a further test series, the influence of the throughput quantity upon the temperature differences between nozzle plate on the one hand and melt and heating box on the other hand was examined with the same installation (with aluminum sealing ring). Table II shows the average values of the measurings.

TABLE II Temperature difference in 0., between nozzle plate and (1) Melt (2) heating box Wei ht veloeit of flow ./min.:

I32 Y u? 21. 7

The substantial dependence of the nozzle plate temperature upon the throughput quantity makes it evident that the melt participates considerably in the heating of the nozzle plate.

Example 3 The installation according to the invention was compared with the known installation at four spinning places during which process a titer of 40/10 den. was spun which corresponded to a throughput quantity of 13.8 g./min. The values set forth in Table III are average values taken from the measuring data. The average values for the temperature differences were determined from the differences of the individual values and not from the left In the case of the new construction, the temperature of the nozzle plate was higher than that of the melt at two of the four spinning places, in one case by 3.6 C., in the other case by 0.9 C. which evidently has to be attributed to the fact that the contact between auxiliary case and contact surface was especially good.

The first example shows that the direct heat transfer at the metallic sealing surface is of special importance. But in the case of the constructions which have become known, the heat flow was not sufficient for the heating of the nozzles for which reason, as is especially evident from Example 2, the melt had to contribute to this heating to a considerable extent. In contrast, Example 3 shows that when the conditions according to the invention are maintained the throughput rate-as especially shown by the two cases with higher nozzle temperature than melt temperatureis practically of no importance. Since the temperature of the heating medium may be considerably lower than in the case of the known installations, it is also guaranteed that undesired local overheating of the melt is avoided.

It is a further object of the invention to provide a device for the execution of the process, consisting of a melt spinning head heated by means of a liquid or gaseous medium, with a separate pump block and nozzle unit. The device is characterized by the fact that the pump block and nozzle unit can be heated separately and over large contact surfaces in which case the nozzle unit is connected to the pump block by a melt line variable in its length which melt line can be pressed in sealing manner on the intake port of the nozzle unit, simultaneously bringing the latter into intimate contact with the contact surface, at the side opposite to the contact surface by means of a stretching device, and in that below the nozzle plate an opening heated all around for the passing through of the filaments is set up in the heating box extending in a manner known in itself up to below the nozzle unit, the walls of which opening run parallel or approximately parallel to the threads emerging from the nozzle. In a special embodiment the nozzle unit in a manner known in itself consisting of nozzle plate, bracket plate and filter unit, besides an intake piece according to the invention, is combined in an auxiliary case. In a special model, the melt line, variable in its length, at its lower end showing a pressure piece which can be pressed on the inlet piece of the nozzle unit by means of a pressure device shows one or several spiral windings for the obtaining of the variability of the length; in another model, the variability of the length is obtained by means of an expansion piece, similar to a stuffing box, constructed out of two tubes gliding in one another in sealing manner.

Because the separate heating of the melt line and the nozzle unit over substantial contact surfaces guarantees satisfactory heat transfer, it is also possible to obtain separate heat cycles. This can be accomplished merely by dividing the heating box by means of a partition. This is particularly useful where the heating of the melt to the spinning temperature preferably takes place only in the nozzle unit.

By means of the enclosed drawing, the invention is explained in more detail. In the drawing:

FIGURE 1 is a section through a melt spinning head according to the invention;

FIGURE 2 is a special model of the expansion piece for the melt line variable in its length;

FIGURE 3 is a section through a melt spinning head similar to FIG. 1 in the case of which through setting up of a partition two separate heating cycles are created; and in FIGURE 4 the course of the lines of the same temperature in a melt spinning heat is shown corresponding to FIG. 3 at stationary operation.

As is shown in FIG. 1, heating box 1, 2, 3 encloses interior space 6 for the reception of the pump block 7, 8 and of the nozzle unit 24 to 30, which space is in customary manner sealed in heat-insulating manner. The connections for the heating medium are not shown in the drawing. Opening 5 at the upper end of interior space 6 accommodates the melt line which is connected with the intermediate piece 8 located in front of the pump over washer 9.

The nozzle unit consists of nozzle plate 25, bracket plate 27, filter unit 28 and inflow piece 29 and is C0111]- bined in an auxiliary case 24. On the inside at the upper edge a multipart pressure plate 30 may be inserted in a recess by means of the screws 32 in order to hold the nozzle unit in the auxiliary case. Washer 26 serves to seal off the auxiliary case.

Below the nozzle plate, an opening 4 is located in the heating box which is proportioned in such a manner that the filaments can pass through without wall contact. This opening is likewise heated all around and its walls seal at the upper end exactly with the bottom surface 34 of the interior space 6 into which the auxiliary case 24 with the nozzle unit is placed.

From the intermediate piece 8 a melt line 10 leads to the inflow piece 29, which line shows a spiral winding 11. Because of this, it is elastically variable in its length.

The lower end of the melt line opens into a pressure piece 12 at the outer sides of which, lying parallel to the drawing plane, respectively a cylindrical pin, being in alignment with one another, is placed. Above the auxiliary case 24 a bearing block 15 is attached to the inner wall of the heating box. A pressure device consisting of the double lever 14, a horizontal draw pin set up at the front end of this lever in appropriate bores, of a return spring, on the one hand attached to the bearing block and on the other hand touching the double lever 14, and of a tension lock 18, 19, 23 is attached in swiveling manner to the bearing block 15, connected with it in such a manner that it can be swiveled around the horizontal axis 16 of the bearing block 15. The lower bolt 19 of the stretching device is seated in a slot 22 in the extended inner wall 2 of the case. At a distance from the center of rotation 16 which corresponds to the distance of the pins 13 of the pressure piece 12, the two side jaws of the double lever 14 show coaxial bores fitting on the pins 13.

When the nozzle unit is changed, the tension lock first of all is loosened by turning nut 23, the head 21 of the lower bolt 19 is then pulled out of slot 22 and the tension device is either swung upward or is removed or in the case upward if the front end of the double lever is of appropriate construction. Now the double lever 14 and therewith pressure piece 12 is lifted oif washer 33 located between inflow piece 29 and pressure piece 12 by the effect of spring 17. Auxiliary case 24 can be removed toward the side (in the drawing toward the right side).

After inserting a new auxiliary case 24 with nozzle unit, the tension lock 18, 19, 23 is again tightened, therewith pressure piece 12 is pressed against the washer with its bottom surface and simultaneously the bearing surface 27 of the auxiliary case 24 is pressed against the plane bottom 34 of interior space 6 whereby a tight connection between pressure piece 12 and inflow piece 29 as well as an intimate contact of the auxiliary case 24 with the plane bottom 34 is obtained.

In the case of the model shown in the drawing, on the left side between auxiliary case 24 and inner wall 2 of the heating box a slot 35 is provided in order to obtain exactly defined conditions with regard to the heat transmission. This slot, however, is not absolutely necessary since because of the heat accumulation in the angle 'the temperature dilference becomes very small even in the case of the lateral contacting of the auxiliary case, especially since the shortest route for the heat flow toward the nozzle plate is through contact surface 37. In addition, it may be advantageous in the case of setting up of the slot 35 to provide a stop edge 51 (FIG. 3).

In the model shown in FIG. 1, the variability of the length of the melt supply line 10 results from spiral winding 11. It has become evident that generally one loop is sufficient, however, it may be advantageous to provide two or more.

Another possibility for varying the length of line 10 is shown in FIG. 2. A cylindrical slide piece 38 is set up at the shortened lower end of melt line 10 coming out of intermediate piece 8. In order to avoid dead corners its bore is enlarged from the diameter of melt line 10 over a conical part 42 and ends in a very thin-walled end piece 41. Cylindrical slide piece 38 sits in the very accurately adapted bore 40 of a small tube 39 in such a manner that it is slidable in longitudinal direction and sealed by sealing rings 43, the small tube 39 being rigidly connected to pressure piece 12 at its lower end. Inner bore 40- of small tube 39 passes at the lower end again over into the inner diameter 45 of melt line 10 via cone 44.

In particular in the case of spinning of quickly decomposing or strongly afterpolymerizing polymers, it can be advantageous to keep the melt supply line with intermediate piece 8 and spinning pump 7 at a lower temperature than the nozzle unit. This is made possible in a simple manner by partition 46 (FIG. 3) which now divides the heating space into an upper part 49 and a lower part 50. Simultaneously a division of the interior space into the upper part 57 and the lower part 58 results, in which case the two interior spaces are connected with one another through, for example, a cylindrical opening 47 for the melt line 10. The two heating spaces have separate inclusions for the heat media not shown in the drawing. Naturally it is also possible with a heating box divided in such a manner to spin with uniform heating box temperature when the two heating spaces are connected to the same heat cycle in series or parallel.

FIG. 4 shows the temperature distribution in space 58 containing the nozzle unit of an installation according to FIG. 3, in this case the slot 35 being omitted. For the reasons already mentioned and in particular because the contact pressure of the lateral face onto the perpendicular inner wall of the heating box is relatively small in comparison with the contact pressure on the base surface according to the invention, this does not lead to any measurable changes of the temperature course. The lines of equal temperatures 53 to 56 are provided with numerical values and supply, together with the examples, a picture of the effect of the measures according to the invention.

We claim:

1. In a method for spinning organic polymers by means of melt spinning units heated with a liquid or gaseous medium, the improvement which comprises separately heating by heat conduction the melt conveying means and the spinning unit, and supplying heat over radiation surfaces below the filament outlet and substan tially parallel to the emerging filaments to counteract the radiation of the nozzle surface.

2. The method as in claim 1, wherein polymers which rapidly decompose or strongly afterpolymerize at spinning temperatures are fed as melt to the actual spinning unit with a temperature which lies below the spinning temperature and are heated up to the spinning temperature immediately before filament formation.

3. Apparatus for spinning organic polymers which comprises in combination: a melt spinning head including a separated pump block and nozzle unit; means for separately heating said pump block and said nozzle unit over large contact surface by means of a liquid or gaseous medium; a melt conduit connecting said pump block and said nozzle unit, said melt conduit being variable in its length; pressure means for pressing the melt conduit in sealing relationship onto the inlet opening of said nozzle unit on the side opposite the heat conducting contact surface of said nozzle unit; pressure means serving to bring the nozzle unit into intimate contact with said heat conducting contact surface; and an opening defined by heated walls below the nozzle unit for the passage of filaments from said unit.

4. An apparatus as in claim 3, wherein said melt conduit includes at least one elastic spiral winding.

5. An apparatus as in claim 3, wherein the heating box is divided into two heating segments by a partition above the nozzle unit and means to supply heat separately to said segments.

6. Apparatus as in claim 3 wherein said pressure means includes a spring loaded tension arm, one end of said tension arm being functionally attached to locking means.

7. Apparatus as in claim 3 wherein said melt conduit includes an expansion member consisting of two tubes slidably mounted one Within the other.

References Cited UNITED STATES PATENTS 594,888 12/1897 Millar. 2,437,687 3/1948 Dreyfus et al. 2,437,704 3/1948 Moncrieff et al. 2,611,928 9/1952 Merion et al. 2,953,428 9/1960 Hunt et al. 3,010,147 11/1961 Davies et al. 3,130,448 4/ 1964 Tomlinson. 3,257,487 6/1966 Dulin. 3,360,597 12/1967 Jones et al.

FOREIGN PATENTS 816,016 7/1959 Great Britain.

824,432 12/ 1959 Great Britain.

903,427 8/ 1962 Great Britain.

973,085 10/1964 Great Britain.

JULIUS FROME, Primary Examiner J. H. WOO, Assistant Examiner US. Cl. X.R. 188; 264-25 

